Presence of salt, diesel fuel may be link to salt cavern
A 381-foot-deep sinkhole that emerged last week near the Bayou Corne community is filled primarily with salt water mixed with traces of diesel fuel, while the muck and vegetation visible at the surface is only six inches deep, Assumption Parish officials said Monday.
A nearby 20-million-barrel Texas Brine Co. LLC of Houston salt cavern, which was plugged in 2011, was filled with brine, a water-salt mixture, for structural integrity, company officials have said.
Some closed salt caverns also have diesel fuel at the top as a “pad” to prevent erosion of the salt from the brine, said John Boudreaux, director of the Assumption Parish Office of Homeland Security and Emergency Preparedness.
The disclosures Monday may further point to Louisiana Department of Natural Resources officials’ suggestions Friday that the sinkhole, which has a diameter of 372 feet, was caused by the possibly failed cavern.
“It’s suspect,” Boudreaux said.
Parish officials took more precise measurements of the hole Monday, which swallowed up one acre of cypress forest. They also obtained the analyses of back water samples taken on Saturday that indicated the presence of diesel and oil on the surface of the slurry.
Boudreaux said water in the slurry area also contains chlorides at levels 10 to 20 times the concentration of normal water. Chloride is one of two elements in the chemical compound that makes up salt.
Sonny Cranch, spokesman for Texas Brine, said company officials have been informed of the hole’s size and contents of the water but said he could not comment further.
“All I can say is we have received the information, and we are going to analyze that information and proceed accordingly. We still want to get an image of what is going on below,” he said.
Cranch said Texas Brine officials met extensively with DNR officials on Monday.
He said the company is trying to decide what kind of sonar-like underground imaging equipment to use to examine the site. The company also plans to use an imaging system that can be employed form the air.
Gov. Bobby Jindal declared a state of emergency Friday after the slurry was found and DNR ordered Texas Brine to try to find the problem and remediate it.
The slurry was found Friday morning after a foul diesel smell pervaded the area. For two months prior, earth tremors were reported and natural gas bubbled up from Bayou Corne, Grand Bayou and a nearby water well.
Fears the slurry would widen quickly and endanger wells holding flammable natural gas and other hydrocarbons prompted parish officials to call for an evacuation on Friday evening.
The evacuation remains in effect but parish officials are not forcing people to leave.
Boudreaux said parish officials have estimated that about half the 350 people in the Bayou Corne community along La. 70 South have evacuated. A shelter was opened Saturday morning at Belle Rose Middle School but no one has come to use it yet.
Nancy Malone, American Red Cross spokeswoman, said Monday many who have left have gone with family and friends, but the shelter is on standby.
Short on cash after recently buying land and setting up a mobile home at Bayou Corne, Linda and Wallace Cavalier packed up their camper Friday and are at a trailer park just down La. 70 from Bayou Corne near Pierre Part.
Linda Cavalier, 52, said she and her husband are staying next to her brother and his wife and family in the park.
While the park costs $20 per day, she said that will add up over a month and, like some other residents, said she wants to see what officials say 6:30 p.m. Tuesday during a meeting at St. Joseph the Worker Catholic Church Hall in Pierre Part.
“We’re waiting for the meeting Tuesday night to see if they can give any answers on exactly who is responsible, what is going on and how long they think it is going take to resolve the matter and move forward from there,” she said.
Cavalier said if the process takes too long, they may have to move in with family because she can’t afford an extra $600 per month to stay in the trailer park.
Shelly Hernandez, 41, and her husband, Tim, 46, have remained in their home south of La. 70 even as neighbors left.
They have three dogs and two exotic birds. Shelly Hernandez described herself Monday as being stuck between staying and moving as she tries to find a suitable place for her pets.
She said the whole situation is “mindboggling” and has been causing her a lot of stress, but added it is hard to assume the added expense of leaving when she is not forced to do so.
“We cannot just leave. I am not going to abandon my house when it is still sitting there, when we don’t have to leave, when we’re not forced to leave. They don’t pay my bills,” Hernandez said.
The watery sink hole was discovered the day after building “swarms” of shallow, small earthquakes ceased, said Stephen Horton, research scientist with the University of Memphis Center for Earthquake Research and Information.
The center has been working the U.S. Geological Survey to monitor the tremors.
He said the number of earthquakes had been building from tens per day around July 12 to several hundredper day — most too small to be felt — before they stopped about 2 p.m. Thursday.
Boudreaux estimated the slurry emerged between 3 and 6 a.m. Friday.
Horton said the close proximity in time between the emergence of the slurry and the halt in quakes is “suggestive,” though he said he could not say why they stopped.
He added that the fact the tremors were shallow, at a depth of a half-mile, makes it possible the tremors were man-made, not natural, though it is not evidence of that.
Horton said he has seen such swarms of earthquakes before in other places.
“To have it happen in Louisiana, obviously, it’s going to take some explanation,” he said.